~until 8,000 years ago- food-gathering

~8,000 years to present- food producing

5000 BC- make boiler pots

7000 BC- beer

3500 BC- wine

3000-1200 BC- salt for preservation

1000 BC- preservation of meats with snow/smoking

1100- Ergot poisoning (grew in wheat, caused gangrene)

1793- Clostridium Botuliniun (blood sausage; air pockets)

1795- Heat preservation (kill spores; canning)

1860- pasteurization (mild heating; won't denature proteins)

1675 Leewenhoek- microscope, described bacteria

1875 Frederick Cohn- endospores; Pasteur- microorganisms spoiled French wine

1880-1890- Koch postulates (microorganisms, diseases, isolation, reisolation)

1940's- TEM (higher resolution transmission electron microscope); visualized viruses (filterable agents)

• salmonella
• clostridium botulinium
• staphylococcus aureus
• bacillus cereus
• clostridium perfringens

Emerging foodborne pathogens

• E. Coli
• Campylobacter
• listeria monocytogenes

• cooking
• canning
• pasteurization (used in combination with other methods, preservatives)
• fermentation
• freeze-drying
• modified atmosphere packaging
• irradiation

Fermentation

• 22 billion Ga's of beer
• 2.2 million tons of cheese
• 90 million pounds of pickles

Food borne illnesses

• 48 million cases
• 3000 deaths
• 128,000 hospitalizations

Spoilages- lose 1/3 of world's supply

USDA-

• FSIS: meat, poultry, egg products
• APHIS: plant and animal pests and diseases

FDA- fresh produce, seafood, imported foods

EPA- pesticides

Department of Commerce- National Marine Fisheries Service

• stable/ nonperishable: sugar flour
• Semi perishable foods: potatoes, nuts
• perishable foods: meats, milk, fish

plant sources-

• surfaces of fruit
• pores of tubers

animal sources-

• skin, hair, GI, milk ducts, tears

environmental sources-

• air, water, insects, equipment, etc.

molds, yeasts, lactic acid bacteria

            - pseudomonas, alcaligines, micrococcus, erwinia,bacillus, clostridium, enterobacter

dominant type and affected by:

- presence of diseases, delay between harvesting and washing, unfavorable storage and transportation conditions

• internal tissues - sterile
• digestive tract- salmonella, campylobacter, listeria, yersinia
• animal hide/ feather
• lymph nodes

Fish- scales, digestive tract

Shellfish- digestive tract, because they are filter feeders

-the types are affected by water quality, feeding habits, and seasons

- Major pathogens: vibrio parahaemolyticus, v. vulnificus, v. chloerae

1. air- dust particles containing bacterial endospores, fungal spores, yeasts
2. soil- molds, yeasts, bacteria; variation in types and numbers
3. sewage- fertilizer, enteropathogenic bacteria and viruses
4. water- used in production, processing; pseudomonas, alcaligenes
5. humans- processing, restaurants, stores; staphylococcus, salmonella, E. Coli, Hepatitis A
6. Food ingredients- intro spoilage and pathogenic microorganisms
7. equipment- microbes introduced during harvesting processing, transportation, storage

(mold) spoilage of grains, jams, cured hams, nuts, fruits, vegetables, some mycotoxins

• a. oryzae- sake production
• a. niger- produce beta-galactosidase

(mold) brown- black rots of stone fruits

some produce mycotoxins

(yeast) spoilage of foods of high acidity, high salt, high sugar content; rancidity of butter and dairy products

forms pellicle on liquid surface

enteric diseases (norwalk)

liver disease (Hep A)

polio and echovirus can be transmitted through foods

• gram negative bacteria
• rods
• found in soil
• usually effects refrigerated fresh products

• gram negative bacteria
• rods
• aquatic environment
• intestines of fish

• gram negative bacteria
• rods
• found widely in nature, raw milk, poultry products
• found in fecal matter

• gram negative bacteria
• rods
• found in marine and coastal water
• seafoods

• gram negative
• s-shaped rods
• found in poultry, milk, shellfish, cattle, swine, water

• gram positive bacter
• spore-forming rods
• aerobes
• found in soil, dust, water, fresh and processed foods

• gram positive bacteria
• non-spore forming rods
• processed meat

• gram negative rods
• C. Freundii- most prevalent species in foods (veg & fresh meat)

• gram positive
• rods
• spoiling vegetable and meat products

• gram positive
• cocci
• widely distributed

• gram positive
• rods
• plants (soft root)

• gram negative
• rods
• yellow to red colonies
• plants, spoils refrigerated vegetables and meats

• gram positive
• cocci
• pink, orange, red colonies
• salt tolerant**

• gram negative
• short rods
• sometimes classified as acinetobacter

• gram negative
• rods
• intestines of human & animals
• vegetables and meats

• gram negative
• rods
• widely distributed among foods, soil, water, spoiling many foods

• gram negative
• rods
• nonmotile 
• meat, poultry, fish, water

• gram negative
• rods
• red colonies
• S. liquefaciens- spoil refrigerated vegetables and meat products

• gram negative
• rods
• aquatic or marine habitats

• lactococcus
• leuconostoc
• lactobacillus
• pediococcus

• E. Coli
• Bacillus
• Campylobacter
• clostridium
• listeria
• salmonella
• shigella
• staphylococcus
• vibrio
• yersinia

1. lag phase
2. log phase (increases)
3. stationary phase (stays the same)
4. death phase (decreases)

During the log phase:

N- Number of organisms

T_d- generation time

µ- specific growth rate

• reduce the pH so the bacteria can't grow
• lower the temperature (10C will decrease growth by 2X)
• lower the initial bacteria population (pasteurization)

• optimal µ- 2.3, t_d- 0.3
• limited nutrients µ- 0.2, t_d- 3.46
• psychotrops (5°C) µ- 0.023, t_d- 30

Factors that relate to the food itself

• pH
• a_w
• oxidation-reduction potential (Eh)
• nutrients
• antimicrobial constituents
• biological structures

• most near neutral
• organic acids enter the cell in protonated form
• when pH falls below critical pH, intracellular proteins become denatured

• homeostatic mechanisms pH>6
• Acid tolerance response (ATR) pH 5.5-6.0
• Synthesis of acid shock protein pH of 3-5

• increased lag phase
• cells are more sensitive to toxic agents
• young cells are more susceptible

acidic- fruits, soft drinks, vinegar, wine

>5.6- meat, poultry, fish, shellfish

more basic- vegetables

p/p₀

-equal to the equilibrium relative humidity (ERH)

• the amount of free water available